glossary

term description
attribute todo
class todo
constructor todo
instance todo
instance variable todo
method todo
object todo
state todo

abstract base classes

notes

Attribute
Data that is associated with an instance
Accessed using object.attribute
A variable
Can have class attributes or instance attributes
accessed in the same way via a ‘dot’
If same name used for both class and instance attribute then instance attribute is accessed first = attribute lookup order
print dir(x)

Augmented assignment
E.g. replace x = x + 1, with x += 1

Class
A blueprint for an instance - an ‘instance factory’
Class constructor functions conventionally start with a capital letter
Classes are also objects

Decorators
A processor that modifies a function
Start with @
E.g for modifying the default binding that instance methods provide: 
@classmethod takes the class as input not the instance
@staticmethod requires no args and does not work with the class or the instance

Encapsulation
One of the three pillars of OOP
Refers to the safe storage of data (as attributes) in an instance
E.g. setter methods to safely set/modify instance attributes

Getter method
A method that gets attribute values from the instance

Inheritance
One of the three pillars of OOP

__init__
Special constructor method that allows us to initialise attributes at the time an instance is constructed
Called automatically whenever a new instance is constructed 
Optional - you don’t have to use it if you don’t need it
(an example of a ‘magic’ function)
(Underscores signify private method, intended for use internally)

Instance
a constructed object of a given class

__main__ 
refers to the namespace of the script currently being executed

Method
a callable attribute defined in the class
allows you to change the state of the instance
A method on an instance always implicitly passes the instance as the first argument to the method
When the function is defined in the class, the instance argument is represented by ‘self’
‘self’ is the instance upon which the method was called
Instance methods are known as ‘bound’ methods- i.e. they are bound to the instance upon which they are called

Method resolution order (MRO)
The order of lookup when an object inherits from multiple classes
Depth first

None
When a function doesn’t return anything it actually returns the None value

Object
a unit of data (i.e. attributes) 
of a particular type (i.e. an instance of a class) 
with associated functionality (i.e. methods)

Object-Oriented Programming (OOP)
A paradigm for code organization and design
Data organised into objects 
Functionality organised into methods
Helps manage complexity
Primary paradigm for software design

Polymorphism
One of the three pillars of OOP
Use the same interface for different classes - e.g. use len() on a string or a list.
E.g. call dir(obj) and you may see things like __len__, which means you can access the obj.__len__() method via the built-in function len - i.e. len(obj)

Setter method
A method that sets attribute values of the instance

State
the values of the attributes of an instance

Type
indicates the class the instance belongs to